Coolbrazz - Walmarts up here won't work on Lexus, Mercedes, Audi etc., not even oil changes or tires. They don't like the cost of fixing their inevitable screw ups, and they say the owners are too particular. To me, that says everything I need to know. If I don't change it myself, it goes to the Dealer or my long time and trusted independent. I too am very particular, I don't want some untrained, pimple faced 16 year old touching my cars.

As far as the new style battery testers, they are easier to use, that is why everyone switched but they are no where near as good as the old toaster type.

 

May I suggest a sure way to get your answer? Disconnect your battery for a few minutes. Pretty sure that will give you what you want to know.
I agree with your frustration with not being able to get a simple answer to your question.

 

Here's the problem: this car was a very generous gift from members of my family who are wealthy and don't think twice about paying what Lexus charges for service. I would never, ever, have bought this car. I want a car with a windshield that keeps the bugs out of my teeth, gets me from place to place reliably, and doesn't cause terror every time it needs maintenance. For people like me, Lexus is a horrific waste of money we'd rather spend on other things.

So I'm trying to have my cake and eat it too, as the saying goes. I'm doing back flips to replace the battery at a fair price while not screwing up the car and ending up forced into thousands of tragically wasted dollars at the Lexus dealer. I've seen the maintenance records for this car, it has not had many problems but when it does, bend over and grab your ankles!!

As soon as I get past this issue I'm going to trade this puppy in for something more economical with a warranty. I wanted to do this day-one but I also did not want to offend people that gave me an extremely generous gift.

 

You can have required maintenance done at a Toyota Dealer if you like.

 

Thanks for the info! I should not have assumed the diagnostics system would warn me and my second mistake was assuming the previous owner must have replaced the original battery by now (this car has been meticulously maintained). I should have verified that.

The sudden death of the battery remains a mystery. No load testing, wasn't even in the bay very long. And the kicker, despite the age of the battery, thirty minutes earlier the car started effortlessly, lights had full brightness when the engine was off, etc. Zero indication of a failing battery.

 

Perhaps it’s because operating under low voltage conditions can cause erratic (unpredictable) electrical behavior so my hypothesis is this: if the battery is reasonably charged (battery is going but hasn’t operated extensively while on the verge of erratic electrical behavior) then most settings might remain stored for a few minutes, long enough to swap batteries without losing the volatile memory settings. However, if the low battery has been permitting quite erratic electrical behavior, then the volatile settings may not be stored long enough to allow a battery swap without losing a lot of settings. Ergo, different answers from some folks. Just my hypothesis though.

Regardless, the battery must be changed. Whether settings are lost or not, it must be changed. I’ve had good luck with Interstate battery service centers; their folks seem competent to swap batteries with a minimum of disconnected time and their prices are reasonable IMO.

 

Tried that. Guess what they want just for registering the new battery in the computer? $200. Total cost with battery and labor would have been close to what I think Lexus charges (about $700). So far none of my nearby Lexus dealers will answer their phone, their automation only phone system wants me to schedule an appointment online or with a scheduling clerk. I've left a message twice (two different dealers nearby) asking (nicely) for the cost to replace the battery on my year/model and those messages have been ignored like crunchy peanut butter in a nursing home.

 

My humble opinion: a free 2016 Lexus that was apparently well maintained that needs a new battery? I'd put in a new battery and enjoy a beautiful car. Don't have to take it to a Lexus dealer for maintenance, a local, trusted shop or Toyota dealer would be fine.

 

Absolutely nothing on the market compares to the reliability and longevity of Toyota/Lexus vehicles with just basic maintenance. I’d be very cautious about replacing it for the long haul.

I’ve never taken my Lexus to a dealership for maintenance. Oil changes every 5-7K miles are done at a local shop. Battery replacements? Handled on my driveway without any issues whatsoever.

 

If you don't mind expanding upon this just a bit I would greatly appreciate it, this may give me the information I've been trying to get at.

1) Is your Lexus 2016 or newer?
2) Do you own a compatible ODB scanner to reset the battery to new (and how much did that cost?) ?
3) Did you maintain power during the swap or how long without power?

I always changed the battery in my old Honda 2002 Honda CRV, a grandmother could swap those batteries. But that was a very simple car. I would imagine it is also easy to swap a battery in an old Lexus. On the other hand, I have been lead to believe 2016 and newer Lexus have complicating issues. For example, if you don't set the new battery flag they will over charge the new battery. I've also read if power is not preserved during the swap there can be loss of settings which impact engine performance. True? I don't know. That's what I'm trying to find out before testing speculations on my car that might lead to dealer visits I can't afford.

When I was young I did brake jobs, battery changes, tune-ups, etc. Now I'm 64, retired, living in a condo with no tools and no place to work on a car. For my last Honda I had a cheap ODB scanner that worked great and was easy to understand. I always replaced the battery myself and when I rarely went to the dealer for service I knew and understood any codes that were present in the computer before I went in. I prefer to understand the issue at hand so I don't have to trust the service shop.

 

1. My 2020 Lexus RX was brand new when I bought it and now has about 65,000 miles.
2. I own a scan tool that I bought years ago when I drove German vehicles, offering endless coding opportunities. Although there’s not much to code in a Lexus, it still lets me track some real-time parameters.
3. I haven’t had to replace the battery in my car yet since it’s working fine, but I plan to do it as a preventive measure before winter. It can get quite cold here in NE Pennsylvania, so I don’t want to take any chances.

Besides being a doctor, cars are my true passion, even in my mid-50s. I enjoy spending my free time in my son-in-law’s garage. He’s an awesome kid and a great mechanic. Watching him replace batteries in various Toyota/Lexus models has been insightful. I recommend checking out Victor G.’s YouTube channel. He’s a master-level technician for Toyota/Lexus, and his battery replacement tutorial for the Lexus RX aligns with my observations.

I understand your concern about resetting potentially important engine settings when the battery is disconnected however nothing will happen at all. Battery replacement is a very straightforward and matter of unscrewing 2 nuts, removing positive and negative clams, pulling the battery out and replacing it with the new battery. If the battery is out for a long period, the car will adapt and learn your driving patterns within a few days once reconnected.

P.S. As I mentioned earlier, and I’m sure hundreds of thousands of other Toyota/Lexus owners would agree, nothing on the market is proven to be more reliable than these vehicles. I would be very cautious about replacing a car with legendary reliability with anything less reliable. Find a good local mechanic, build some friendship and have him to perform basic maintenance, such as regular oil changes, engine and cabin filter replacements, and the occasional differential lubricant replacement.

I recently replaced the gear oil in the front and rear differentials, which was extremely simple. It was just a matter of draining the old fluid and filling it with new. In all honesty, it seemed unnecessary as the drained liquid was the same color as the new one I put in.

 

I'm retired, on a fixed income. This car is loaded to the hilt, HUD, and every single thing that could be motorized is motorized except the gas cap and hood. Cameras and sensors everywhere. I know you are right about overall reliability for Toyota's products. But even if the car is treated well, it's a bit of a lottery isn't it? This car incurred a $3K steering wheel repair that nobody caused, it just plain failed. When something does go wrong on a loaded car like mine with a "prestige" brand on it, costly repair bills are the norm. I'm not disagreeing with you, I'm pointing out it's a lottery and it depends upon how much cash reserves you have to cover losing the lottery. Everyone's personal situation is different.

An independent shop that's competent and honest is wonderful. I've experienced that joy myself from time to time over the years. Not lately. They are very hard to find. These days shops seem to be staffed mostly with inexperienced techs that aren't crazy about their job or employer.

 

I've disconnected my battery twice. The only issue I had were the lights on the dashboard about calibration. After driving it for one minute the lights went off. Nothing serious at all..

 

Get your battery tested.

 

artem123 - Thanks for taking the time to write a thoughtful reply, much appreciated! My car has been down for a couple days now, I'm going to plunge ahead with the assumption this is a normal battery swap + computer registration which the discount battery chains claim they can do on this car.

Myself I'm a computer and electronics geek. I don't mind spending money on that stuff at all. But every penny spent on a car and it's many related expenses just kills me. I don't even enjoy driving to be honest. I've been on the lookout for a place to move where I could do without a car completely that is also safe and pleasant.

I search through computer forums almost every day in relation to my programming work and web design. But I never post questions, it's rarely productive and frequently unpleasant. Instead I comb through numerous responses to similar questions. That works for me when I'm in my element and can instantly judge the quality of the responses but I'm no car expert (or even enthusiast lol) so after seeing countless conflicting threads in various forums I became desperate enough to post a question.